Visual Studio Code – Using VS C++ functions in Inno Setup

I’m trying to replace some functions made in LazarusLib with functions written in C++ for Inno Setup installer.

So I created a Dynamic-Link Library (DLL) project in Visual studio and added the following code:

InstallerFunctions.h:

extern "C" {
    __declspec(dllexport) bool __stdcall CheckPortAvailable(int Port);
}

InstallerFunctions.cpp:

#include "pch.h"
#include "framework.h"
#include "InstallerFunctions.h"
#include <windows.h>
#include <winsock.h>
#include <string>
#include <fstream>

bool __stdcall CheckPortAvailable(int Port) {
    WSADATA WSAData;
    SOCKET Sock;
    sockaddr_in SockAddr;
    int ErrorCode;

    if (WSAStartup(MAKEWORD(2, 2), &WSAData) != 0)
        return false;

    Sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (Sock == INVALID_SOCKET)
        return false;

    ZeroMemory(&SockAddr, sizeof(SockAddr));
    SockAddr.sin_family = AF_INET;
    SockAddr.sin_addr.s_addr = INADDR_ANY;
    SockAddr.sin_port = htons(Port);

    ErrorCode = bind(Sock, reinterpret_cast<sockaddr*>(&SockAddr), sizeof(SockAddr));
    closesocket(Sock);

    WSACleanup();

    return (ErrorCode != SOCKET_ERROR);
}

This project builds successfully. The project is configured to output the DLL file to Output
Then I added this to Inno Setup script:

[Files]
Source: "..InstallerFunctionsOutputInstallerFunctions.dll"; DestDir: "{app}"; Flags: ignoreversion

The path is correct. Then I declare the function as following:

function CheckPortAvailable(Port: Integer): Boolean;
external 'CheckPortAvailable@files:InstallerFunctions.dll stdcall delayload';

When I try to call CheckPortAvailable I get the following error:
Could not call proc.

I tried to use DLL explorer to find the functions I require and DLL explorers are able to find the functions. Any idea what else can I try?

Edit:
It appears that the function is recognized, so the issue defenitly lies in C++ project: